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fix rounding in TA calculation

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This commit is contained in:
Thomas Schlichter
2021-10-27 17:30:05 +02:00
parent c1ae09621e
commit 107f20ad29
1 changed files with 6 additions and 6 deletions
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openair1/SCHED_NR/phy_procedures_nr_gNB.c
+6 -6
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@@ -403,8 +403,6 @@ void nr_fill_indication(PHY_VARS_gNB *gNB, int frame, int slot_rx, int ULSCH_id,
pthread_mutex_lock(&gNB->UL_INFO_mutex);
int timing_advance_update, cqi;
int sync_pos;
NR_gNB_ULSCH_t *ulsch = gNB->ulsch[ULSCH_id][0];
NR_UL_gNB_HARQ_t *harq_process = ulsch->harq_processes[harq_pid];
NR_gNB_SCH_STATS_t *stats=get_ulsch_stats(gNB,ulsch);
@@ -412,19 +410,20 @@ void nr_fill_indication(PHY_VARS_gNB *gNB, int frame, int slot_rx, int ULSCH_id,
nfapi_nr_pusch_pdu_t *pusch_pdu = &harq_process->ulsch_pdu;
// pdu->data = gNB->ulsch[ULSCH_id+1][0]->harq_processes[harq_pid]->b;
sync_pos = nr_est_timing_advance_pusch(gNB, ULSCH_id); // estimate timing advance for MAC
int sync_pos = nr_est_timing_advance_pusch(gNB, ULSCH_id); // estimate timing advance for MAC
// scale the 16 factor in N_TA calculation in 38.213 section 4.2 according to the used FFT size
uint16_t bw_scaling = 16 * gNB->frame_parms.ofdm_symbol_size / 2048;
int sync_pos_rounded;
// do some integer rounding to improve TA accuracy
int sync_pos_rounded;
if (sync_pos > 0)
sync_pos_rounded = sync_pos + (bw_scaling / 2) - 1;
else
sync_pos_rounded = sync_pos - (bw_scaling / 2) - 1;
sync_pos_rounded = sync_pos - (bw_scaling / 2) + 1;
if (stats) stats->sync_pos = sync_pos;
timing_advance_update = sync_pos_rounded / bw_scaling;
int timing_advance_update = sync_pos_rounded / bw_scaling;
// put timing advance command in 0..63 range
timing_advance_update += 31;
@@ -449,6 +448,7 @@ void nr_fill_indication(PHY_VARS_gNB *gNB, int frame, int slot_rx, int ULSCH_id,
LOG_D(PHY, "Estimated SNR for PUSCH is = %f dB (ulsch_power %f, noise %f)\n", SNRtimes10/10.0,dB_fixed_x10(gNB->pusch_vars[ULSCH_id]->ulsch_power_tot)/10.0,dB_fixed_x10(gNB->pusch_vars[ULSCH_id]->ulsch_noise_power_tot)/10.0);
int cqi;
if (SNRtimes10 < -640) cqi=0;
else if (SNRtimes10 > 635) cqi=255;
else cqi=(640+SNRtimes10)/5;